Theobromine, a chemical in the methyloxantine family of alkaloids, occurs naturally in raw and processed chocolate. These chemicals have been found to dilate blood vessels, allowing increased blood flow. In addition, this group of chemicals increase urine output by stimulating kidney activity. Like most chemicals, however, there are risks to consuming methyloxanthines in high doses.
The discovery of the benefits of this chemical is not recent. Before the development of more effective medications, vascular conditions, such as hardening of the arteries and insufficient blood flow to the heart, were treated with the chemical. Other conditions that are caused by constriction of blood vessels, such as asthma and migraine headache, were also treated with methyloxanthines. The resurgence of the chemical's popularity is largely due to the development of concentrated theobromine in capsule and tablet form.
Besides traditional usages, theobromine has recently been shown to increase insulin sensitivity and reduce blood pressure. Letters published in the American Journal of Clinical Nutrition indicated that these results were noticeable in five of seven healthy subjects. Further studies may ascertain the effects of methyloxanthines on patients with preexisting insulin resistance and hypertension.
Negatively, there is some evidence that consumption by pregnant women may have significant adverse effects on the development of the fetus. Specifically, a study by the National Institute of Tuberculosis and Lung Diseases in Poland found that laboratory animals that ingested large amounts of theobromine and other methyloxanthines showed impaired development of new blood vessels. In addition, the arms and legs of the offspring were stunted in size, and the animals showed several irregularities in immune system function.
In addition, theobromine is the chemical that makes chocolate potentially fatal to dogs who are unable to break down the chemical in the liver. This condition, although much rarer, can also occur in predisposed humans. In general, the levels of the methylxanthines in even high quality chocolates are unlikely to cause poisoning in people. Unfortunately, however, supplements containing 20 to 30 times the amount of these chemicals are now commercially available. At these levels, even healthy individuals risk a reaction.
The source of theobromine also determines its overall benefit to an individual’s health. The high levels of fat and refined sugar in milk chocolate likely overshadow any benefit that the chemical may have on insulin levels and blood pressure. Dark chocolate, however, often contains higher levels of the chemical and lower levels of sugars. In that case, the benefits may balance just enough to allow guilt-free snacking.